SIP30 involvement in vesicle exocytosis from PC12 cells
Ning Guo and Dr. Lei Yu of Rutgers Department of Genetics and the Center of Alcohol and Substance Use Studies are working to understand processes involved in neuropathic pain such as vesicle exocytosis and associated proteins. Vesicle exocytosis includes the release of neurotransmitters from neurons, or neuron-secretory cells, for the facilitation of communication between neurons and/or cells. SNAP25 (Synaptosome-associated protein of 25 kDA) is a SNARE (soluble N-ethylmaleimide-sensitive factor attachment receptor) protein, and both play an important role in synaptic vesicle exocytosis. There are many proteins that interact with SNAP25 in this cellular process. There are also interacting proteins that play a more regulatory role. SIP30, which has been associated with neuropathic pain (pain caused by nerve damage that sustains overtime), has been identified to interact with SNAP25 and is similar to the regulatory interacting proteins in the vesicle exocytosis process. Thus, it is hypothesized that it may play a regulatory role in vesicle exocytosis. In this study, neuron-like PC12 cells from rat adrenal chromaffin cells were used to evoke exocytosis in order to model a system that investigates the role of SIP30 in vesicle exocytosis.
P12 cells were obtained and transfected with control siRNA or SIP30 siRNA. These cells were then used to examine the exocytosis of recycling vesicles from PC12 cells. Results showed that the number of released vesicles was reduced by 65% in the SIP30 siRNA group compared to the control group. The SIP30 siRNA group also had a 40% reduction in their releasing rate constant. A reduction in the releasing rate constant demonstrates a diminished speed of preparing vesicles into a readily releasable status, which would subsequently lead to a decrease in the number of vesicles being released. These cells were also used to examine the kinetics of recycling vesicle endocytosis and the replenishment of releasable vesicles from endocytosis recycling vesicles. Results showed that the endocytosis of vesicles and the replenishment of releasable vesicles through endocytosis were not affected by SIP30 siRNA transfection. From these results, it appears that SIP30 only affects the process of vesicle exocytosis and has no effect on the process of vesicle endocytosis. This shows that SIP30 is highly likely to be a regulator of vesicle exocytosis through its interactions with SNAP25 by docking to SNAP25 proteins, and relaying vesicle fusion signals to its partners. This docking capacity may also be an underlying reason for SIP30’s ability to modulate neuropathic pain.
The full article can be accessed here: https://www.sciencedirect.com/science/article/pii/S2405580823001954
Guo, N., & Yu, L. (2024). SIP30 involvement in vesicle exocytosis from PC12 cells. Biochemistry and Biophysics Reports, 37, 101614–101614.